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PubMed1995

Effect of quaternary ammonium salts and amine oxides on Pseudomonas aeruginosa.

Two quaternary ammonium salts, viz (1-methyldodecyl) trimethylammonium bromide (ATDBr) and tetramethylammonium bromide (TMABr), as well as two amine oxides, (1-methyldodecyl)dimethylamine oxide (ATDNO) and trimethylamine oxide (TMANO), were tested for their inhibitory activity on a Pseudomonas aeruginosa strain isolated from nosocomial infections. Only those compounds with long alkyl chains in their molecules (ATDBr and ATDNO) showed antimicrobial efficacy. In subinhibitory concentrations both compounds inhibited incorporation of [14C]-adenine and [14C]-leucine as precursors of macromolecular biosynthesis. Endogenous respiration of the cells was more sensitive to both agents than the respiration of various substrates. Among the virulence factors only the production of phospholipase C was inhibited by sub-MICs, while the activities of elastase and proteinase were stimulated until the inhibitory concentrations were reached. The short-chain analogues TMABr and TMANO did not show these effects. It is suggested that the production of virulence factors is affected by amphiphilic compounds due to their antimicrobial activity.

Cross Infection↗
PubMed1996

Biomodulation of the toxic and nutritional effects of small bowel bacterial overgrowth in end-stage kidney disease using freeze-dried Lactobacillus acidophilus.

Small bowel bacterial overgrowth (SBBO), well known to occur in end-stage kidney failure, is responsible for producing uremic toxins and contributing to the patient's decreased nutritional well-being. In this study, 8 hemodialysis patients were treated with a course of oral Lactobacillus acidophilus (LBA) in an attempt to alter this SBBO. LBA treatment was effective in lowering 2 compounds generated in vivo. Serum dimethylamine (DMA) levels dropped from 224 +/- 47 to 154 +/- 47 micrograms/dl at the end of LBA treatment (p < 0.001). Nitrosodimethylamine, a carcinogen, levels also decreased significantly from 178 +/- 67 (untreated) to 83 +/- 49 ng/kg (after LBA treatment). Patients nutritional status, assessed as serum albumin, body weight, caloric intake, midarm muscle area (MAMA) and appetite improved modestly, but not significantly. LBA changed small bowel pathobiology by modifying metabolic actions of SBBO, reducing in vivo generation of toxins and carcinogens and promoting nutrition with no adverse side effects.

Analysis of Variance↗
PubMed1988

The allergens in cosmetics.

The ingredients responsible for allergy to cosmetics were determined in 119 patients suffering from cosmetic-related contact dermatitis. Most reactions (56.3%) were caused by skin care products, followed by nail cosmetics (13.4%), perfumes (8.4%), and hair cosmetics (5.9%). Preservatives were most frequently implicated (32.0%), followed by fragrances (26.5%) and emulsifiers (14.3%). By far the most important cosmetic allergen was Kathon CG, (a preservative system containing, as active ingredients, a mixture of methylisothiazolinone and methyl chloroisothiazolinone) reacting in 33 patients (27.7%). Other frequent causes of cosmetic-related contact allergic reactions were toluenesulfonamide/formaldehyde resin in nail hardener and/or nail lacquer (15 patients [12.6%]), and oleamidopropyl dimethylamine, an emulsifier in baby body lotion (13 patients [10.9%]).

Adolescent↗
PubMed2002

Synthesis of a novel potential tridentate anthracene ligand, 1,8-bis(dimethylamino)-9-bromoanthracene, and its application as chelate ligand for synthesis of the corresponding boron and palladium compounds.

A novel potential tridentate ligand, 1,8-bis(dimethylamino)-9-bromoanthracene, was synthesized. The key steps are as follows: 1) dimethylamination of 1,8-dibromo-9-methoxyanthracene by a modified Buchwald's method to afford 1,8-bis(dimethylamino)-9-methoxyanthracene, and 2) reduction of the methoxy group by LDBB (lithium di-tert-butylbiphenylide) followed by treatment with BrCF2CF2Br. The corresponding 1,8-bis(dimethylamino)-9-lithioanthracene, which should be a useful versatile tridentate ligand, could be generated by treatment of the bromide with one equivalent of nBuLi. The lithioanthracene reacted with B-chloroborane derivatives to give three 9-boryl derivatives. Although we recently reported that the crystal structure of 1,8-dimethoxy-9-B-catecholateborylanthracene was a symmetrical compound with the almost identical two O-B distances (2.379(2) and 2.441(2) A), the newly prepared 1,8-bis(dimethylamino)-9-borylanthracene derivatives clearly have unsymmetrical structures with coordination of only one NMe2 group toward the central boron atom. However, the energy difference between the unsymmetrical and symmeterical structures was found to be very small based on 1H NMR measurements, in which symmetrical anthracene patterns in the aromatic region (two kinds of doublets and a triplet) and a sharp singlet signal of the two NMe2 groups were observed even at -80 degrees C. 1,8-Bis(dimethylamino)-9-bromoanthracene itself can be a versatile ligand for transition metal compounds. In fact, direct palladation of the bromide took place by the reaction with [Pd2(dba)3].CHCl3 in THF to give the 9-palladated product. X-ray crystallographic analysis of the Pd compound showed that the square planar palladium atom was coordinated in a symmetrical fashion by both NMe2 groups (Pd-N bonds are 2.138(5) and 2.146(5) A).

Journal Article↗
PubMed2006

Reaction of azole heterocycles with tris(dimethylamino)borane, a new method for the construction of tripodal borate-centred ligands.

Reaction of 2-mercapto-1-methylimidazole (methimazole) with tris(dimethylamino)borane, B(NMe2)3, provides the tetrahedral dimethylamine adduct of tris(methimazolyl)borane, [(Me2HN)B(methimazolyl)3]. By contrast, imidazole, 2-methylimidazole, 2-chloroimidazole and benzimidazole provide the homoleptic tetra-azolyl systems H[B(azolyl)4], and the same product is obtained even when a substoichiometric quantity of the heterocyle is employed. The change in reaction outcome is correlated with the variation of basic pKa for the heterocycles. A simple acid-base reaction with elimination of HNMe2 is proposed for the reaction with the weakly basic, but more strongly acidic, methimazole. However, for the more strongly basic imidazoles, initial coordination of the heterocycle imine nitrogen to the weakly Lewis acidic boron centre in B(NMe2)3 to form the tetrahedral adduct [(azole)B(NMe2)3] is proposed. The greater availability of the NMe2 lone pairs in this species results in increased basicity and a rapid reaction with further heterocycle to provide the observed H[B(azolyl)4] products. For 2-nitroimidazole, the low basicity (and increased N-H acidity) results in the formation of [(HNMe2)B(2-nitroimidazolyl)3] on reaction with B(NMe2)3, analogous to the product formed with methimazole. Both [(HNMe2)B(methimazolyl)3] and H[B(benzimidazolyl)4] have been structurally characterised by single crystal X-ray crystallography. This chemistry has been exploited to provide a new synthesis of borate-centred tripod ligands, whereby N-methylimidazole is used to activate B(NMe2)3 to reaction with methimazole to form the new ligand [(N-methylimidazole)B(methimazolyl)3] in good yield and a complex of this ligand with Ru(II) has been structurally characterised.

Journal Article↗
PubMed2006

Facile and versatile annulation of the imidazole ring: Single and sequential cyclization reactions of Fischer carbene complexes with 1,4-diazafulvenes.

We examined the reactivity of dimethylaminodiazafulvene 1 toward Fischer alkenylcarbene 2 and alkynylcarbene 3 complexes. Diazafulvene 1 reacts with alkenylcarbenes 2 through a formal [6+3] heterocyclization in a regio- and stereoselective manner to afford dihydroimidazo[1,2-a]pyridines 4. Acid-promoted dimethylamine elimination in compound 4 c gives rise to the aromatic imidazo pyridine 5. A likely mechanism for this reaction is a 1,2-nucleophilic addition/[1,2]-shift metal-promoted cyclization sequence. On the other hand, diazafulvene 1 and alkynyl carbenes 3 undergo a [6+2] cyclization to afford pyrrolo[1,2-a]imidazole carbene complex 6 that can be readily oxidized to the corresponding esters 7. When enynylcarbenes 3 e-i are treated with diazafulvene 1, consecutive and diastereoselective [6+2]/cyclopentannulation cyclization reactions take place affording new polycyclic complex systems 8, 9, and 12 that can be appropriately demetallated to the corresponding imidazole-based polyfused systems 10, 11, and 13 respectively. Finally, enynylcarbenes 3 d,f undergo consecutive [6+2]/[5+1] cyclization reactions with diazafulvene 1 and tBuNC, respectively, to yield tetracyclic adducts 14 and 15. All these processes result in high yields and provide a route to the preparation of imidazopyridines and pyrroloimidazoles as well as other polycyclic molecules that contain imidazole groups, which are interesting from a pharmacological and biological point of view.

Journal Article↗
PubMedDate not supplied

Recovery of liver function in partially hepatectomized rats evaluated by aminopyrine demethylation capacity.

Aminopyrine demethylation was investigated in rats after a 70% hepatectomy to assess possible parallelism between the recovery of mass and function. Tests were performed by analyzing 14CO2 exhalation from 0.1 microCi per 100 gm of body weight of [dimethylamine-14C]aminopyrine given intraperitoneally with incremental doses of unlabeled drug. Early after 70% hepatectomy, Vmax was reduced by 52%. This discordance between mass and function was not due to extrahepatic aminopyrine demethylation, since liver exclusion reduced demethylation of aminopyrine to nearly nil. Whether it results from increased liver blood flow in the remnant liver is less clear: portacaval anastomosis provoked an identical fall in Vmax and liver blood flow, but aortal-portal fistula which increased liver blood flow by 70% did not modify Vmax. The early increase in Vmax could be related to a "hepatotrophic" factor of splanchnic origin which increased after partial hepatectomy and decreased after portacaval shunt. After the early period, Vmax, expressed per gram of actual liver weight, returned to control range. Throughout regeneration (4 to 144 hr), no modification was observed in Km nor in cytochrome P-450 concentration. Enzymatic induction with phenobarbital increased the demethylation capacity more than liver weight in intact and regenerating liver. Except for the first hours after partial hepatectomy or after enzymatic induction, the aminopyrine demethylation capacity directly correlated with liver mass and may be useful in evaluating liver regeneration in vivo.

Aminopyrine↗
PubMed2003

Cyclopalladated compounds as chemotherapeutic agents: antitumor activity against a murine melanoma cell line.

Palladacycle compounds obtained from N, N-dimethyl-1-phenethylamine (dmpa), phenyl-2-pyridinyl-acetylene and 1-phenyl-3-N, N-dimethylamine-propine, respectively, were complexed to 1, 2 ethanebis (diphenylphosphine) (dppe) ligand to synthesize antitumor cyclopalladated complexes that were tested in vitro and in vivo against syngeneic B16F10-Nex2 murine melanoma cells of low immunogenicity implanted subcutaneously in mice. Complexes were not toxic to mice injected 3 times i.p. with as much as 60 microM/animal/week. Of 3 cyclopalladated complexes that were inhibitory in vitro at low concentrations (<1.25 microM), complex 7a was the most active in vivo, delaying tumor growth and prolonging animal survival. In vitro, binucleate complex 7a caused a collapse of respiratory activity with an abrupt decrease of extracellular acidification on short incubation (up to 100 min), followed by DNA degradation after 24 hr. The apoptosis-like reaction to this Pd-complex was not accompanied by increased levels of caspases 1 and 3. Complex 7a bound to a bacterial plasmid DNA, causing late conformational changes after 24 hr. Two other complexes with different C, N-cycles were also apoptotic and 2 binucleated ones were inactive. These results introduce the palladacycle-dppe complexes as promising antitumor drugs with exquisite structural specificities and for action in vivo and in vitro.

Animals↗
PubMed1989

Circumvention of adriamycin resistance by dipyridamole analogues: a structure-activity relationship study.

Dipyridamole restores sensitivity to Adriamycin (ADR) in drug-resistant cells. In an effort to elucidate the relationship between activity and chemical structure of dipyridamole, the ability to enhance the growth inhibitory effect of ADR, in multidrug-resistant (MDR) P388 murine leukemia cells, was determined for 43 derivatives and related compounds. Since both substituted pyrimidopyrimidines and pteridines enhanced the growth-inhibitory effect of ADR in drug resistant cells, the core skeleton may not be directly involved and rather serve as a carrier for the substituents connected with this activity. The exact positions of the active substituents on the core skeleton did not seem to be critical for exertion of the activity. Activity was dependent on the presence of 3 tertiary amine groups. However, not all tertiary amines showed the same potency which might be related to the degree of basicity and/or the spatial structure of these groups. The most active derivatives carried piperidine and pyrrolidine groups while derivatives with thiomorpholine, 3-hydroxypiperidine or dimethylamine groups had low activity. Activity was also dependent on the presence of a substituent with partial electronegative charges as found in a diethanolamine group. However, this function could be carried out, with even higher efficiency, by a substituent containing 6 pi electrons.

Animals↗
PubMed1994

Dietary factors and the risk of glioma in adults: results of a case-control study in Melbourne, Australia.

In a population-based case-control study of 416 incident gliomas in adults carried out in Melbourne, Australia, between 1987 and 1991, 409 age-sex-matched case-control pairs (243 male and 166 female) had adequate data available to examine associations between the dietary intake of N-nitroso compounds, N-nitroso precursors, other nutrients including N-nitroso inhibitors, and the risk of glioma. Dietary intakes were based on the reported frequency of consumption of 59 food items. Increased odds ratio (OR) were observed in males who consumed high levels of bacon, corned meats, apples, melons and oil. OR less than unity were observed in men consuming cabbage and cola drinks, and in women who consumed wholegrain bread, pasta, corned meat, bananas, cauliflower, brocoli, cola drinks and nuts. Generally, N-nitroso associations were greater in men and micronutrient associations were greater in women. Elevated OR in men, but not women, were associated with the intake of N-nitroso dimethylamine (NDMA), retinol and vitamin E. The intake of nitrate (largely of vegetable origin) was protective in women but not in men. When analyzed using multiple logistic regression, the association with NDMA intake in males was not modified by dietary micronutrient intakes. In females, beta carotene alone, though not directly associated with risk, modified the effect of NDMA. On balance, this study added only limited support to the N-nitroso hypothesis of glial carcinogenesis.

Australia↗
PubMed1984

Herbicide-quinone competition in the acceptor complex of photosynthetic reaction centers from Rhodopseudomonas sphaeroides: a bacterial model for PS-II-herbicide activity in plants.

A select group of herbicides that inhibit photosystem II also act at the acceptor side of the reaction center (RC) from the photosynthetic bacterium Rhodopseudomonas sphaeroides, with much the same relative specificity as in plants. These include the triazines and some phenolic compounds. The proposal that herbicides inhibit the electron transfer from the primary quinone (QA) to the secondary quinone (QB) by competing for the secondary quinone binding site--the B-site--[5], is tested here with terbutryn, the most potent of the triazines. Competition between terbutryn and ubiquinone (Q-10) was observed using the kinetics of the back-reaction as a measure of inhibition. The model includes binding equilibria before and after flash activation. The binding constants for the preflash (dark) equilibria, for reaction centers in 0.14% lauryl dimethylamine-N-oxide (LDAO), were KDi = 0.8 microM terbutryn, KDq = 2 microM Q-10; both are detergent-concentration dependent. After flash activation, binding equilibrium is not fully restored on the time scale of the back-reaction because terbutryn unbinds slowly. This gives rise to biphasic decay kinetics from which koff for terbutryn was estimated to be 3 sec-1. Titrations of the rate of the slow back reaction indicated that the post-flash equilibrium is less sensitive to inhibitor, in a manner that is independent of the much stronger binding of the semiquinone, Q-B, and indicative of a direct effect of the redox state of QA on the affinity of the B-site for ligands. However, the effects on KLi and KDq could not be separated: either KLi greater than KDi or KLq less than KDq. Some triazine-resistant mutants have been isolated and are described. All appear to be herbicide binding site mutants. Whole cells and photosynthetic membrane vesicles (chromatophores) exhibit a 10-50-fold increase in resistance to triazines due, in large part, to an increase in the rate of unbinding (koff). The modifications of the binding site appear to diminish the affinity of the B-site for ubiquinone as well as terbutryn. It is concluded that bacterial RCs are a useful model for the study of herbicide activity and specificity.

Binding, Competitive↗
PubMed2002

Combined ab initio/empirical approach for optimization of Lennard-Jones parameters for polar-neutral compounds.

The study of small functionalized organic molecules in aqueous solution is a useful step toward gaining a basic understanding of the behavior of biomolecular systems in their native aqueous environment. Interest in studying amines and fluorine-substituted compounds has risen from their intrinsic physicochemical properties and their prevalence in biological and pharmaceutical compounds. In the present study, a previously developed approach which optimizes Lennard-Jones (LJ) parameters via the use of rare gas atoms combined with the reproduction of experimental condensed phase properties was extended to polar-neutral compounds. Compounds studied included four amines (ammonia, methylamine, dimethylamine, and trimethylamine) and three fluoroethanes (1-fluoroethane, 1,1-difluoroethane, and 1,1,1-trifluoroethane). The resulting force field yielded heats of vaporization and molecular volumes in excellent agreement with the experiment, with average differences less than 1%. The current amine CHARMM parameters successfully reproduced experimental aqueous solvation data where methylamine is more hydrophilic than ammonia, with hydrophobicity increasing with additional methylation on the nitrogen. For both the amines and fluoroethanes the parabolic relationship of the extent of methylation or fluorination, respectively, to the heats of vaporization were reproduced by the new parameters. The present results are also discussed with respect to the impact of parameterization approach to molecular details obtained from computer simulations and to the unique biological properties of fluorine in pharmaceutical compounds.

Amines↗
PubMed2004

Novel rearrangements of an N-oxide degradate formed from oxidation of a morpholine acetal substance P antagonist.

Compound 1 [5-[2(R)-[1(R)-(3,5-bistrifluoromethylphenyl) ethoxy]-3(s)-(4-fluorophenyl)morpholin-4-ylmethyl]-3h-[1,2,3] triazol-4-ylmethyl]dimethylamine represents a new class of potent, orally active substance P antagonists, which possess a characteristic structural feature-a cis-2-alkoxy-3-arylmorpholine core. The oxidative degradation of 1 in drug substance and formulations was found to occur through the two trialkylamine oxides, which undergo secondary degradations to give rise to observed degradation products. In this study, the five primary degradation products of the N-oxide 2 formed from the oxidation of the morpholine core of 1 were identified by LC/MS and MS/MS. The N-oxide 2 undergoes novel thermal rearrangements, which were proposed to follow elimination/addition mechanisms. An unusual, facile [1,3]-sigmatropic rearrangement was also demonstrated.

Mass Spectrometry↗
PubMed1978

Oxidative degradation of pharmaceutically important phenothiazines I: Isolation and identification of oxidation products of promethazine.

The thermal degradation of promethazine in water in the presence of oxygen was studied. After degradation, the products were isolated by TLC. Identification was carried out by comparison of the isolated compounds with reference compounds. Melting points, spectral data, and polarographic and chromatographic behavior were compared. The following products were identified: 10-methylphenothiazine, phenothiazine, 3H-phenothiazine-3-one, phenothiazine 5-oxide, promethazine 5-oxide, 7-hydroxy-3H-phenothiazine-3-one, acetaldehyde, formaldehyde, and dimethylamine.

Chemical Phenomena↗
PubMed1982

Synthesis and antitumor testing of 3-methenylthiochroman-4-one-1,1-dioxide.

Treatment of thiochroman-4-one-1,1-dioxide (II) with paraformaldehyde and dimethylamine hydrochloride in isopropyl alcohol at reflux afforded directly in 80% yield the dimeric dihydropyran (IV), corresponding to the dimerization of the target compound 3-methenyl-thiochroman-4-one-1,1-dioxide (III). Neither the monomer III nor the expected Mannich base, 3-dimethylaminomethylthiochroman-4-one-1,1-dioxide, were isolated under conditions of the reaction. The monomer III could be prepared in 55% yield by sublimation of the dimer IV at 230-250 degrees; however, redimerization slowly occurred at room temperature. The dimer IV was also prepared by the use of paraformaldehyde and N-methylanilinium trifluoroacetate. The monomer III was found to be marginally active at 10 mg/kg/day versus Ehrlich ascites tumor growth in mice.

Animals↗
PubMed1986

Molecular orbital calculations of proton transfer involving amines as models for the clastic binding of opiates with their receptor.

Semi-empirical (CNDO) molecular orbital calculations, based on a previously reported ammonia-amine model system, were performed on an extended series of methyl-, ethyl-, and propylamines as models for the analgesic receptor. Methyl-, dimethyl-, and trimethylamines were chosen to represent the opiate molecules. Interatomic distances were varied within normally expected biological values. The results for the larger systems are similar to more elaborate calculations previously reported using smaller molecules. At internuclear distances of greater than 0.275 nm, the potential energy curves had two minima. At 0.2731 nm, the optimized N-N distance, the "depth" of the minima in the potential energy curve were not as great. Energy differences as well as population differences suggest deviation from the currently stated clastic binding theories mechanism for the analgesic response of the tertiary amines. The dimethylamine energy profile and population data indicate that the hypothesis of N-demethylated opiate as the active molecule needs further consideration and investigation. Investigation of larger systems is also indicated to develop increasingly realistic models for the analgesic response.

Amines↗
PubMed2004

Differential protonation and dynamic structure of doxylamine succinate in solution using 1H and 13C NMR.

A protonation and dynamic structural study of doxylamine succinate, a 1:1 salt of succinic acid with dimethyl-[2-(1-phenyl-1-pyridin-2-yl-ethoxy)ethyl]amine, in solution using one- and two-dimensional 1H and 13C NMR experiments at variable temperature and concentration is presented. The two acidic protons of the salt doxylamine succinate are in 'intermediate' exchange at room temperature, as evidenced by the appearance of a broad signal. This signal evolves into two distinct signals below about -30 degrees C. A two-dimensional 1H-1H double quantum filtered correlation experiment carried out at -55 degrees C shows protonation of one of the acidic protons to the dimethylamine nitrogen. A two-dimensional rotating frame 1H-1H NOE experiment at the same temperature reveals that the other proton remains with the succinate moiety. Comparison of the 1H and 13C chemical shifts and the 13C T1 relaxation times of the salt with those of the free base further substantiate the findings.

Carbon Isotopes↗
PubMed1995

Ion selectivity of the channels formed by pardaxin, an ionophore, in bilayer membranes.

Using the method of bilayer membranes at the tip of a patch pipette, the properties of the ionic channels produced by the ionophore toxin pardaxin were investigated. At low toxin concentrations, voltage-dependent, single-channel events were measured. The current-voltage curves were non-linear when determined in Tris-Cl solution, but were linear in K(+)-HEPES solution. Using asymmetric ion solutions, the ionic selectivity of pardaxin channels was estimated from the reversal potentials obtained. The sequence of the relative permeabilities for monovalent cations was Tl+ > Rb+ > Cs+ > K+,NH4+ > methylamine+ > Li+ > dimethylamine+ > Na+. Except for Li+, the selectivity sequence fitted the cations relative hydrated size. For bivalent ions the permeability of Ba2+, Sr2+, and Mn2+ relative to Mg2+ changed according to the relative hydrated size. For anions the selectivity sequence was I- > NO3- > Br- > Cl- > ClO4- > SCN- > BF- > HCOO- > F- > CH3COO-. The selectivity sequence for the small anions (I-, NO3-, Br-, Cl-) was different from their hydrated size. Pardaxin channel showed a modest ion selectivity between small anions and cations (PK:PCl:PNa = 1.28:1.00:0.56). Pardaxin is proposed as a biophysical model to study ionic channel selectivity.

Cell Membrane Permeability↗